WASHINGTON U.S. Senate Majority Leader Mitch McConnell on Tuesday said "nobody wants terrorists to have firearms" and that he was open to suggestions from experts on legislation that could address the problem.

McConnell, a Republican, made his remarks amid blistering attacks by Democrats on the lack of action in Congress on legislation to prevent suspects on "watch lists" purchasing guns or explosives.

The debate in Congress over firearms was reignited on Sunday after a gunman in Orlando, Florida armed with an assault rifle killed 49 people at a gay nightclub and injured 53 others before he was shot dead by law enforcement officers.

The assailant, New York-born Omar Mateen, had been investigated by the FBI for 10 months in 2013 and 2014 amid claims that he had connections to foreign militant groups.

Democrats are pressuring Republicans in the Senate and House of Representatives to quickly bring up legislation closing a loophole that allows those on "no fly" watch lists to purchase weapons in the United States.

The Democrats are targeting a Justice Department appropriations bill this week, hoping to add an amendment prohibiting such gun sales. A similar effort last December failed.